(1) Field of the Invention
The present invention relates generally to a guard for a string trimmer, and in particular to a pivotal guard that can be attached to existing string trimmers of various designs to prevent damage to flowers, shrubs and other vegetation in front of the trimmer.
(2) Description of the Prior Art
String trimmers are comprised of a rotary cutting head that feeds at least one monofilament line or string of nylon or other plastic. A motor rotates the cutting head at high speed to rotate the string along a generally horizontal, circular pathway. The cutting head is located at the lower end of an elongated handle or shaft, while the motor, which may be electric or gasoline powered, is normally mounted at the top of the handle.
Grass, weeds and other vegetation are readily cut by contact by the rotating string. However, the string can also cause damage to the bark of shrubs and trees, and to flowers and other vegetation that the user desires not to cut. In order to address this problem, various guards have been proposed that can be positioned in front of the rotary path of the string to prevent the string from contacting objects on the opposite side of the guard.
The following patents describe prior art string trimmer guards:
______________________________________ U.S. Pat. No. Inventor(s) ______________________________________ 4,756,084 Morita 4,872,265 Powell 4,890,389 Whitkop 5,048,187 Ryan 5,060,383 Ratkiewich ______________________________________
String trimmers are sold by various manufacturers and are of many different designs. For example, the handle or shaft of some string trimmers is comprised of a generally vertical section adjacent the cutting head curving to join an upper, rear section that is at an angle, e.g., of from about 30 to 60.degree.. Other trimmer handles are generally straight and extend rearwardly from adjacent the cutting head at a 30 to 60.degree. angle. Different string trimmers also are designed with different cutting radiuses. As a result, a different guard design is required for each style of trimmer.
The guard, to be effective, must be positioned at a sufficient distance from the axis of the cutting head to avoid contact with the string. At the same time, spacing of the guard at an unnecessarily great distance from the string pathway minimizes the cutting efficiency of the trimmer by preventing cutting of grass and other matter close to the object to be protected.
In addition, the guard must provide a large barrier surface between the string and the object to be protected, and must be sufficiently rigid to prevent deflection of the guard when an object is contacted with some force. Prior art guards are inadequate in both respects.
Prior art guards have been designed for attachment to a single type of string trimmer, requiring the manufacture and stocking of a variety of trimmer guard designs. A string trimmer guard, in particular a pivotal guard, that could be easily mounted on a string trimmers of different designs, would be of considerable commercial utility.